Tractors are called upon to perform many tasks besides pulling plows. One of these tasks is that of lifting bins of produce from the field for placement within the cargo space of a pick-up truck. There have been numerous lifting devices adapted for use on a tractor for such lifting purposes.
One type of lifting device is a hydraulically operated tractor mounted forklift. The tractor engine provides the power to drive the hydraulic system. These devices can work well but have several drawbacks. They are normally individually custom fitted to each tractor and thus can be used on only a single tractor. They are also expensive and are cumbersome to mount to and remove from the tractor.
Tractors often come with a powered three point hitch, typically employing a pair of power driven lower arms and an upper, stabilizing arm. The arms are pivotally mounted to the tractor so the distal ends of the arms move vertically approximately two to three feet along a relatively large diameter arc. This source of power and motion has been used for various types of mechanical forklifts specially designed for use on tractors having such powered hitches. These machines, exemplified by U.S. Pat. Nos. 2,472,194 and 2,712,389, typically employ either a scissors or a parallelogram type of operating mechanism. However, many of the available tractor mounted forklifts are time consuming to hook up to the tractor and may loose much of their lifting power at their maximum height.
Thus, what has been missing in the prior art is a forklift assembly for use with a three point hitch on a tractor which is inexpensive, simple to mount to and dismount from the tractor, and maintains its lifting capacity regardless of the height of the load.